Not a silver bullet unless you never let your phone talk to a cell tower - in which case it stops being a phone and starts being a miniature tablet.

At least with Librem 5 you can use the hardware kill switch whenever you need privacy.

It doesn't matter what your phone runs. As long as it's communicating with the network, the carrier knows its location.

Cell towers is far from the only tracking possibility.

Yes but it's the only one that's a requirement if you want to actually use your phone.